Cops were forced to act to disperse rioters upset at a People' Assembly van being blocked by security.

Smoke bombs were thrown and demonstrators - many wearing masks to hide their identity - chanted "Let us out!" after police refused to allow a van join the march route because it did not have security clearance.

Police vans and mounted officers were later sent to Liverpool Road as the protesters refused to move, and a force helicopter hovered overhead.

After about an hour, police searched the van and allowed it to be driven off.

Extra police were drafted into the area today to help police keep the marchers away from the conference.

Snipers guarded the parade on rootftop too in case violence erupted, but the march was said to be mostly peaceful and no arrests were made.